Conversion questions

[naynay12]

Thanks i have cleared that part up, btw yes,i have a 2s and 3s.
So it would be great if someone could clear up my other 2 questions so i can buy the parts asap.
The reason why i want to know if the hpi pinion will hold up on 5s ,is because for a mod1 it is like $50 to Australia,since postage is like $38.
Seeing that my packs are 5000mah with 20c rating,they will be ok for a 20t pinion right?Or will i need to get a lower tooth count pinion?